In X-ray imaging, for example in computer tomography, angiography or radiography, counting directly-converting X-ray detectors can be used. The X-rays or photons can be converted into electrical signal pulses. Besides the counting of events, counting X-ray detectors also enable information about the energy of the detected X-ray quanta to be obtained. New possibilities are thus opened up for the analysis and evaluation of signal pulses in medical imaging.
As converter material for the converter element or the sensor, for example CdTe, CZT, CdZnTeSe, CdTeSe, CdMnTe, InP, TlBr2, HgI2, GaAs or others can be used. The energy of the incident ionizing radiation is immediately converted into electrical charges, so-called electron-hole pairs. A voltage is applied to the converter element, for example for CdTe, CZT, CdZnTeSe, CdTeSe or CdMnTe in the range of −500 to −2000V, between an electrode as a cathode and another electrode as an anode to separate the charges of the electron-hole pairs triggered in the converter element. The cathode can be designed as continuous electrode. The anode can be designed as a pixelated electrode. The voltage or the high voltage is applied to the electrode by way of an external high-voltage source via an electrically conductive contact. X-ray quanta can trigger electron-hole pairs in the converter element by way of energy deposition. The electron-hole pairs are separated by the applied voltage and the charge carriers selected by the polarity of the voltage can be sucked or drifted to the anode. In this way, an electrical signal pulse can be triggered in the read-out and/or the analysis unit. As a rule, the converter element is joined to a read-out and/or an analysis unit flat in a stacking arrangement, for example an integrated circuit (Application Specific Integrated Circuit, ASIC), via solder connections, electrically conducting adhesive or other methods. The electrical signal pulses are evaluated by an analysis unit, for example an ASIC. The stacking arrangement having the converter element and the read-out- and/or analysis unit is connected to a further substrate, for example a circuit board, a ceramic substrate such as, for example, HTCC or LTCC or others. The electrical connections for read-out of the read-out and/or the analysis unit can be formed by way of vias (through silicon via, TSV) or wire bond.
An X-ray detector for image recording of an object irradiated by X-rays which has a number of detector modules arranged adjacently to one another in a longitudinal direction, in a stack formation comprising a sensor layer with a sensor surface, is known from DE 10 2013 226 669 A1, wherein in each case a high voltage can be applied to the sensor surfaces for the detection of X-rays, and wherein an insulation foil which covers the sensor layers on the facing stacking sides of adjacent detector modules transversely with respect to the longitudinal direction is arranged in a gap between two adjacent detector modules respectively.
A detector module for an X-ray detector comprising a sensor layer with a sensor surface in a stack formation, to which a high voltage can be applied for the detection of X-rays, and wherein a related protective foil is arranged on at least two side faces of the stack formation, is known from DE 10 2014 211 602 A1.
A high-tack adhesive mass, based on an adhesive mass containing at least polyisobutylene and at least one tackifying resin, is known from DE 10357321 A1, wherein the molecular weight distribution of the polyisobutylene has two relative maxima, namely one between 50000 and 200000 and a second between 1.0×106 and 3.5×106.
A photon counting detector which has a directly-converting material and a data collection system is known from U.S. Pat. No. 7,696,483 B2.
In the event of mechanical damage, for example if an X-ray detector or a detector module falls and/or is struck against a hard object, the converter element may break into small fragments, particles or dust which can then get into the environment. CdTe, CZT, CdZnTeSe, CdTeSe and CdMnTe are hazardous substances and detrimental to health and so even in the event of mechanical damage, no dust and/or larger particles should get into the environment. Either while handling during production or when replacing a module in a clinical setting, after mechanical damage no small fragments, particles or dust of the converter element should get into the environment. At present, there is still no solution for the problem of mechanical protection. X-ray detectors or detector modules are handled very carefully to avoid mechanical damage.